PLANT PHYSIOLOGY
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- Versione italiana
- Academic year
- 2022/2023
- Teacher
- GIUSEPPE FORLANI
- Credits
- 9
- Didactic period
- Primo Semestre
- SSD
- BIO/04
Training objectives
- Plant Physiology is a field of life sciences that deals with the study of the molecular basis of plant functions, with particular emphasis on the photosynthetic metabolism. Among the issues treated are general aspects, such as the morphophysiology, ecophysiology, biochemistry and molecular biology of plants, and other more specific features, such as the photobiology, bioenergetics, growth regulators and the plant secondary metabolism. The subject deals with the study of both basic mechanisms of the functioning of plants, and practical applications, among which the increase of crop productivity and plant biotechnology.
The main objective of the course is to provide students with the concepts and the knowledge for understanding the main plant functions and the underlying structures at the molecular level, those that allow its autotrophic growth and the completion of its life cycle even in the absence of either the ability to move about, a central nervous system or a closed circulatory system. In this perspective, a special emphasis is placed on distinct plant features that are different from those in animals.
The student is guided toward the understanding of the relationship between structures and functions of plants, with particular attention to ontogeny (the development of tissues and organs, up to the floral transition) and interactions between plants and the environment, with respect to both abiotic (climatic conditions and nutrients availability) and biotic factors (predators and competitors).
Laboratory activity is aimed at improving the knowledge of selected topics covered in the course, and at the same time at acquiring practical skills in performing experimental protocols, using some of the basic techniques for the study of living matter at the biochemical, molecular and cellular levels.
KNOWLEDGE AND UNDERSTANDING
The student:
- will know the proper scientific terminology;
- will know the mechanisms underlying the main biological processes in the plants at the molecular level;
- will know the mechanisms by which plants are able to convert light into chemical energy;
- will know the mechanisms that allow plants to obtain mineral nutrients from the environment;
- will know the main pathways and their integration in both basal and secondary plant metabolism
- will know how plants react to environmental stimuli by means of hormones and photoreceptors.
ABILITY TO APPLY KNOWLEDGE AND UNDERSTANDING
The studenti will be able:
- to use the proper scientific terminology;
- to understand the main physiological processes during plant development;
- to understand and predict the mechanisms by which plants react to changes in environmental conditions;
- to exploit the knowledge of techniques to investigate the main physiological processes in plants and to plan a basic experimental protocol;
- to use the basic techniques in plant biotechnology, such as the establishment of plant cell cultures and seedling growth under axenic conditions. Prerequisites
- Although there are no prerequisites, the student should have basic knowledge of general chemistry, organic chemistry, biophysics and biochemistry, and a solid understanding of both the basics of cell biology, with particular attention to the plant cell, and the scientific method and its terminology.
Course programme
- The lectures will cover the following topics:
Why study plants? (2 h)
Relationships between structures and functions in the plant cell: cell wall; vacuole and tonoplast; plasmalemma; plastids, mitochondria, microbodies and cytoskeleton; the nucleus, the ER and the secretion of proteins (5 h).
The photosynthetic metabolism: photosynthetic pigments, the antenna funnel and the capture of the light; photosystems II and I, and the electron transport chain; NADP+ reduction and the non-cyclic photophosphorylation; the quinone cycle and the cyclic photophosphorylation; CO2 fixation: the Calvin Cycle and its regulation; photorespiratory oxydation and the C2 Cycle; the C4 Carbon Cycle and the Crassulacean Acid Metabolism; mechanisms for dissipating excess light energy; photosynthetic responses to light and carbon dioxide (12 h).
Bioenergetics. Synthesis of starch and sucrose; glycolysis, the pentose phosphate pathway and the citric acid cycle; the mitochondrial electron transport in plants. Water and transport across the cell; water potential; water transport through the xylem. Transport of ions; electrochemical potential; channels and carriers; secondary active transport. Translocation in the phloem. Lipid metabolism and conversion of storage lipids into carbohydrates in the seed (13 h).
Assimilation of mineral nutrient. Soil composition. Nitrogen biogeochemical cycle, nitrate reduction and ammonia assimilation. Biological nitrogen fixation by free-living and symbiotic bacteria. Phosphate assimilation and mycorrhizal symbioses. Sulfur and iron assimilation. Liebig's and diminishing returns laws. Mineral deficiencies and principles of crop fertilization (7 h).
Secondary metabolism and plant defense against pathogens. Cyanogenic glucosides and glucosinolates; terpenes, phenolic compounds and nitrogen-containing compounds. The use of plant cell cultures to produce selected secondary compounds (5 h).
Growth and development. Plant tropisms; auxin, cytokinins and gibberellins; plant cell cultures and plant biotechnology; ethylene and abscisic acid; other plant hormones (8 h).
Plants and the environment. Light perception and signalling by phytochromes and cryptochromes; the control of flowering and floral organ development; circadian rhythms, flowering and vernalization. Stress physiology (6 h).
Lab practice:
Chromatographic separation and spectroscopic characterization of photosynthetic pigments
Light-driven ferricyanide reduction by isolated spinach chloroplasts and evaluation of putative inhibitors of the photosynthetic electron transport Didactic methods
- The course consists of theoretical lessons and guided experimental activities in the Functional Laboratory at the SVeB Department. In more detail, the course load is 72 hours (9 ECTS), 64 hours of which (8 ECTS) are taught the classroom, and 8 hours (1 ECTS) are spent in the laboratory. Classes are held weekly in the classroom, using powerpoint slides.
To help students to assess their level of preparation, at regular intervals 6 lectures are devoted to self-assessment tests: the teacher asks a dozen questions on the topics covered during the last weeks, allowing the students some think time to answer; then, the questions are answered by the teacher, with a quick review of the related subjects, giving the student an immediate feedback on the correctness of his/her answer.
For the laboratory practice, students are divided into classes, and inside the class in groups (maximum 3 students per group). Learning assessment procedures
- The final exam is aimed to verify the student's level of knowledge and understanding of the subject, and the student's ability to discuss and explain the key concepts. The evaluation is expressed in thirtieths (minimum rate 18/30).
The exam may be written or oral, at the student's choice.
The written exam consists of 66 questions with multiple-choice answers (5 possible answers, of which only one is correct). The student will score 0.5 points for each correct answer, with no penalty for wrong answers. At least 36 correct answers are required to pass the exam.
The oral exam if offered both at the end of the course and throughout the academic year. It usually consists of 3 or 4 questions (the first one about the photosynthetic metabolism; the second one about the mineral nutrition; the third one about one of the hormone-regulated processes, and the last one concerning another of the topics covered by the course). The exam is not successfully passed if the student completely fails to answer or address one of the questions, or if he/she simply makes statements without having an adequate understanding of underlying processes. The final score takes into account both the knowledge and reasoning skills demonstrated by the student. Reference texts
- Suggested textbook:
L. Taiz and E. Zeiger, Plant Physiology and Development, 6th edition, 2015, Sinauer Associates Inc, Sunderland MS (previous editions are also suitable).
